Alkyl fluoride production

ABSTRACT

Apparatus and process for contacting a hydrogen fluoride containing vapor stream with water and reacting the resultant mixture with a liquid olefin stream under conditions sufficient for forming alkyl fluoride and thereafter recovering the alkyl fluoride.

United States Patent Carter Sept. 16, 1975 ALKYL FLUORIDE PRODUCTION 2,4l7.875 3/1947 Leonard 260/6516 3,716, 93 2 1973 H .J 'l. 260

[75] Inventor: Cecil 0. Carter, Wann, Okla. 5 utson T ct I /653 6 [73] Assignee: Phillips Petroleum Company,

Bartlesville' Ok]a Primary ExaminerD. Horwltz [22] Filed: Jan. 29, 1973 21 1 Appl. No.: 327,734 57] ABSTRACT [52] US. Cl. 260/653.6 Apparatus d process for contacting a hydrogen fluo- 1 C07C C07C 19/08 ride containing vapor stream with water and reacting [58] Field of Search 260/6536 the resultant mixture with a liquid olefin stream under conditions sufficient for forming alkyl fluoride and [56] R f r n s C t thereafter recovering the alkyl fluoride.

UNITED STATES PATENTS 2/1944 Linn 260/6516 3 Claims, 1 Drawing Figure ALKYL FLUORIDE PRODUCTION In order to prevent waste of valuable catalyst and to minimize emissions of catalyst into the atmosphere or other processing systems, it is desirable to provide an apparatus and method for recovering hydrogen fluoride, used, for example, as a catalyst in HF alkylation, from a vapor stream containing hydrogen fluoride. This invention therefore resides in apparatus and process for removing hydrogen fluoride from a hydrogen fluoridecontaining vaporous stream and recovering said hydrogen fluoride.

Other aspects, objects, and advantages of the present invention will become apparent from a study of the disclosure, the appended claims, and the drawing.

The drawing is a diagrammatic view of an HF alkylation system having apparatus for recovery of HF from a vaporous stream.

Referring to the drawing, an olefin feed stream 2, an isobutane feedstream 4, and an HF catalyst stream 5 are charged to reactor 6 wherein alkylation of the isobutane with olefin occurs. The reaction mass or emulsion comprising alkylation product passes from reactor 6 into settler 8, wherein a lower liquid HF catalyst phase forms and is removed via 5 and cooler 7 and is recycled to reactor 6; and an upper liquid hydrocarbon phase, including alkylation product, saturated with HF, forms. This hydrocarbon phase passes via conduit 10 to reboiled fractionator l4. Debutanized alkylation prodnot is recovered from fractionator 14 via conduit 13; a side draw of vaporous normal butane is removed via conduit 30; and a side draw of liquid isobutane stream is removed via conduit 18 and is recycled to the reaction zone 6. Overhead vapors, from fractionator 14, comprising propane and lighter hydrocarbons and hydrogen fluoride containing stream pass via conduit 20 and condenser 12 into overhead accumulator 22 wherein a lower liquid HF phase is formed, an upper liquid hydrocarbon phase is formed, and noncondensibles are present above the hydrocarbon phase. The liquid HF phase is removed via conduit 24 and recycled (not shown) to reactor 6. A portion of the liquid hydrocarbon phase 23 is used to reflux the upper portion of fractionator 14. Another portion of the liquid hydrocarbon phase, sufficient to rid the system of charged and produced propane, is charged via conduit 32 to the HF stripper 28. Product propane, substantially free of HF is recovered via 34. Vaporous HF and propane are removed from the HF stripper 28 via conduit 36 and are combined with the overhead vapors 20 from fractionator l4 upstream of the condenser 12. Noncondensibles are removed from accumulator 22 via conduit 26. This vaporous stream 26 comprises light hydrocarbons and hydrogen fluoride. This vapor stream 26 cannot be used, e.g., as fuel gas, because of its HF content.

Hydrogen fluoride containing vapor stream 26 is charged to the lower end portion 44 by absorption column 38 having an upper end portion 42 and a lower end portion 44. This column can have contact trays, inert packing and the like to effect proper Contact. A water stream 40 passes into an upper end portion 42 of absorber 38 wherein the downflowing water stream countercurrently contacts the rising vapor stream 26 and removes the hydrogen fluoride from the vapor stream, producing hydrocarbon vapors substantially free of HF, removed from the absorber 38 via conduit 43. This stream 43 can now be used as fuel gas since it is not contaminated with HF. The HF-water extract stream produced in absorber 38 is removed from the lower end portion of absorber 38 via conduit 46 as the first mixture stream and passed to pump 47 along with an HF-water phase 49 described hereinbelow. A portion of the effluent from pump 47 is returned to conduit 40. Makeup water, as needed may be added to conduit 40 via conduit 41. The remainder of the effluent from pump 47 is passed to a reaction zone, in this example represented by an eductor 48, to which is charged a portion of the olefin feed, or other olefin, via conduit 50. In reactor 48, the olefin reacts with the HF which is present in the HF-water extract stream 46, and the mass is passed to separator 54 wherein an upper liquid alkyl fluoride phase forms and wherein a lower water phase forms which is now leaner in HF. This now leaner in HF-water phase is recycled via conduit 49 to pump 47. The produced alkyl fluoride stream is passed via conduit 52 to the reaction zone wherein it is converted into additional alkylate by reaction with isobutane therein.

Reaction conditions in reactor 48 are preferably at a pressure not greater than about 300 psig, preferably in the range of about 150 to 200 psig, and a temperature range of about 50 to about 150F, preferably at about 90 to 1 10F. The olefin to HF weight ratio is preferably about 5 to l to about 40 to l in order to react out the HF from the HF-water extract stream. Preferably the olefin used is isobutylene, but can include any one of propylene, isobutylene, a butylene, and amylenes. Examples of the butylenes can be butene-l, cis-butene- 2, and trans-butene-2. The olefin is preferably added in the liquid form. Recycle of the liquid phase 49 to reaction zone 48 assists in the reaction.

Reactor 6 is operated at a pressure to maintain substantially liquid phase, e.g., above about 150 psig, and at a temperature in the range of about to 150F, usually at about to 1 10F, which allows use of water as the cooling medium in exchanger 7. The isobutane to olefin (plus alkyl fluoride) mol ratio is usually in the range of 4 to 1 up to 25 to 1, preferably about 8 to l to 15 to l. The volume ratio of HF catalyst to total hydrocarbon is usually about 1 to 1 up to about 8 to I, usually about 4 to l to 6 to l These conditions produce the highest octane alkylate.

The absorber 38 is operated in the temperature range of about 50 to about F, more preferably at about 90 to 1 10F and at a pressure less than about 300 psig, preferably in the range of about 150 to 200 psig. The mol ratio of aqueous phase 40 to mols of HF in stream 26 is usually about 1 to l to about 5 to 1. It is desirable to maintain the concentration of HF in the HF-water extract 46 above about 15 weight percent, more preferably above about 25 weight percent, up to about 50 weight percent.

The olefin feed stream 2 can be one of propylene, a butylene, isobutylene, and amylenes, or mixtures thereof. The isoparaffin can be isobutane and/or isopentane.

Typical Plant Operation The vapor stream 26 charged to absorber 38 has the following typical composition:

compfln'lfll Pnunds/Dfly The olefin feed utilized was a mixture of isobutylene Ethane 3% and butene-l. Propane 3073 S This example illustrates that the concentration of HF Hydmgc Flumdc in water should be above about weight percent to effect preferred economical recovery of HF from water The vent gas 43 removed from the absorber 38 containing HF using an olefin containing stream.

the following composition: EXAMPLE ll Reaction of Mixed propylcnwllul lenc ()lelins Component P n /D y \vitli Solutions 01 HF Acid in WUILI' to Produce Alk \l l-'luorides Ethane 396 Pmpunc 2073 HF (olicciitr'ition Hydmgc" Flmridc W114 in Water 5: (10

()lcliii Feed 1 The HF-water scrubbing liquid has the following Aume Pmdu composlnon: Propane ll l2. l l l.) l 1.0 Propylene Z l .7 2 l .4 2 l .0 10.0 lsobutane 27.0 28.3 25.8 2&0 C m "cm P ii-Butaiie 7.0 7.4 8.0 7.3 O p mm 8/ lsobutane+Butene-l I55 I] 7.3 7.0 illii'fiif' :1 *2: :1 :1 Hd Fl d- 50 y rogu] U0" L lsohutyl Fluoride 4.7 9.7 10.7 as Z-Fluorobutanc 0.0 4.1 Residue 0,8 05 0.7 1.) The HF-water extract yield 46 has the following com- Old-m Fmwmmh I Wt. Kl l4.0 27.7 p Fluoride Selectivity.

'71 83.2 100.0 76.] Olefin Feed Purity 5 l .7 wt. 4 olefin Component Pounds/Da 3O Olefin Densit 4.7242 Lbs/Gal. (olefins only) Water I50 Hydrogen Fluoride 100 This example illustrates that as the concentration of HF in the water increases, the conversion of the olefins o to alkyl fluoride increases, but that above about 52 Absorber 38 Operated about 100 F and about weight percent HF in water. the selectivity to fluorides 20 p igdecreases.

Reactor 48 charges about 27.5 barrels per day of liquid olefin (about 50 weight percent olefin) which TABLE I amounts to about 2,800 pounds per day of olefins, and ith recycle 49 th HFL t h d t reactor 48 i The tollowing is a material balance of the process b 450 d d I I b t 100 Unit Capacity 4000 HP!) alkylatc 4 out P 5 P g l Ethane vent 0.75 BBL/1000 13131. alk |utc pounds of HF therein. The reaction is effected in the Alkylate yield 1.8 BBL/BB1. Olefin eductor-mixer 48 at about 100F at about 200 psig. g 'fgg gt'" if $3 1 s I Alkyl fluoride produced (equivalent to 50 pounds/day HF Containing vapor Stream (26) of HF) and unreacted olefin stream is recovered from 45 I l 7 1 1 settler 54 via conduit 52 and charged to reaction ZOne El p 7 1 7 a t anc .96 6. The HF'water phase 49 comprising about 450 Pmpunc 8229 2073 pounds per day water and pounds per day HF is rc- HF Vapor 4 1.99 50 cycled to d it 46, Total 100 100.00 2519 EXAMPLE 1 Reaction of Pure lsobutylene with Solutions of HF Acid and the Formation of lsohutyl Fluoride HF Concentration. Wt. 71 in Water 9.5 20 30 40 53 Olefin Feed Composition. Wt. 71 Average Product isobutane 0.04 0.04 0.03 0.04 0.31 0.06 normal-Butane 0.0 0.0] 0.05 0.0] lsohutylcne Butcne-l 99. 99.8) 97.43 88.17 l-l.0 2.15 IransButcne-Z 0.05 0.04 0,04 0.05 0.5l 0,|0 cis-Butcne-Z 0.0] 0.03 0.10 0.0l lsobutyl Fluoride 0.03 2.4) 1 L0 84.59 96.45 Residue 0.1 0.38 1.22

Total 99.99 100.00 100.00 10000 100.00 100.00 Isobutylene Conversion. Wt. 71 0.01 1.91 8.97 81.98 97.12

lsobutyl Fluoride Selectivity I00 100 9&4 97.) 98.2

TABLE l-Continued The following is a material balance of the process Unit Capacity 4000 BPD alkylatc Ethane vent 0.75 BBL/I000 BBL ulkylatc Alkylntc yield 1.8 BBL/BB1. ()lclin i(.,/olclin ratio 13 BBLS/BBL HF Containing Vapor Stream (26) Liquid Olefin Stream (50) Other modifications and alterations of this invention will become apparent to those skilled in the art from the foregoing discussion and accompanying drawing, and it should be understood that this invention is not to be unduly limited thereto.

What is claimed is:

1. In a process for the production of an alkylate wherein an isoparaffin selected from the group consisting of isobutane, isopentane and mixtures thereof and an olefin selected from the group consisting of propylene, butylene, isobutylene, amylenes and mixtures thereof and an HF catalyst are introduced into a reaction zone and are reacted to form an effluent comprising said alkylate, wherein said effluent is passed into a fractionation zone, wherein said alkylate is withdrawn as a liquid, and wherein a vapor comprising light hydrocarbons and HF is withdrawn from said fractionation zone, I

the improvement which comprises contacting said vapor from said fractionation zone with water at a pressure not greater than 300 psig and at a temperature of about 50 to about F. to form a first mixture comprising HF and water, 7 and reacting said first mixture with an olefin which comprises one of propylene, isobutylene, cisbutene-2, trans-butene-2, butene-l, amylenes or mixtures thereof in an olefin-to-HF weight ratio of 5:1 to 40:1 at a pressure not greater than 300 psig and at a temperature of about 50 to about 150F. to form an alkyl fluoride. 2. A process according to claim 1 wherein said vapor stream is contacted with water in an absorber.

3. A process according to claim 1 wherein said alkyl fluoride is recovered as a product of the process. 

1. IN A PROCESS FOR THE PRODUCTION OF AN ALYYLATE WHEREIN AN ISOPARAFFIN SELECTED FROM THE GROUP CONSISTING OF ISOBUTANE, ISOPENTANE AND MIXTURES THEREOF AND AN OLEFIN SELECTED FROM THE GROUP CONSISTING OF PROPYLENE, BUTYLENE, ISOBUTYLENE, AMYLENES AND MIXTURES THEREOF AND AN HF CATALYST ARE INTRODUCED INTO A REACTION ZONE AND ARE REACTED TO FORM AN EFFLUENT COMPRISING SAID ALKYLATE, WHEREIN SAID EFFLUENT IS PASSED INTO A FRACTIONATION ZONE, WHEREIN SAID ALKYLATE IS WITHDRAWN AS A LIQUID AND WHEREIN A VAPOR COMPRISING LIGHT HYDROCARBONS AND HF IS WITHDRAWN FROM SAID FRACTIONATION ZONE, THE IMPROVEMENT WHICH COMPRISES CONTACTING SAID VAPOR FROM SAID FRACTIONATION ZONE WITH WATER AT A PRESSURE NOT GREATER THAN 300 PSIG AND AT A TEMPERATURE OF ABOUT 50* TO ABOUT 150*F. TO FROM A FIRST MIXTURE COMPRISING HF AND WATER, AND REACTING SAID FIRST MIXTURE WITH AN OLEFIN WHICH COMPRISES ONE OF PROPLYLENE, ISOBUTYLENE, CIS-BUTENE-2, TRANS-BUTENE-2, BUTENE-1, AM YLENES OR MIXTURES THEREOF IN AN OLEFIN-TO-HF WEIGHT RATIO OF 5:1 TO 40:1 AT A PRESSURE NOT GREATER THAN 300 PSIG AND AT A TEMPERATURE OF ABOUT 50* TO ABOUT 150*F. TO ORM AM ALKYL FLUORIDE.
 2. A process according to claim 1 wherein said vapor stream is contacted with water in an absorber.
 3. A process according to claim 1 wherein said alkyl fluoride is recovered as a product of the process. 